The invention relates in general to wireless communication systems and in particular to an RF communication system for receiving and transmitting audio, video and data signals.
Today, wireless data solutions are enabling changes of great scope and depth in our society. Indeed, the wireless information revolution has the potential to democratize the information age like never before. Remotely accessible computers and data systems are becoming more and more available, putting us all on the verge of a world where an unlimited amount of information will be available anywhere, anytime.
Wireless data capabilities are also improving the productivity and accessibility of professionals in the field. The ability to send and receive information over airwaves instead of copper wires is liberating the professionals from their offices, giving them immediate access to databases and streamlining every aspect of their operations. Already, notebook computers equipped with advanced wireless communications software and radio frequency modems have enabled the formation of "virtual offices," offices that are removed from company headquarters. Now, a market analysts can track the stock market in his car while sitting in traffic during his commute to work. An engineer, instead of sitting in his office, can work on a CAD file from the pool side of his home.
The explosion of wireless data communication has been fueled by advance in semiconductor technology and software. These advances have allowed audio and data signals to be transmitted over digital networks in digital language, the language of computers.
Digital and mixed signal systems offer many advantages over old-fashioned analog systems. One important advantage is the ability of digital systems to transmit and receive more information at higher rates. Whereas analog systems are limited to transmitting audio at a rate of 64 Kbps, digital systems can compress audio transmissions and transmit eight times as much information at the same rate. Moreover, faster processors have allowed digital systems to transmit bits at ever increasing rates. By taking advantage of the ability to transmit information more accurately and at higher rates, significant savings have been realized in both switching capacity and ongoing line costs.
Additional advantages have been realized through the use of multiple access techniques such as Time Division Multiple Access ("TDMA") and Code Division Multiple Access ("CDMA"). These techniques allow for multiple users to access a single bandwidth. They also allow for audio and data signals transmitted by a single user to be intermingled. These techniques make better use of scarce airwave space.
A recent development in the wireless information revolution has been the transmission of video signals over the airwaves. This is now being done in the television industry, as near-perfect images are being transmitted digitally on the Ku-band from satellites to home-mounted dishes as small as eighteen inches in diameter. A similar development is occurring in the cellular telephone industry as efforts are being made to add video capability to cellular telephones.
Before quality video capability can be added to cellular telephones, a problem arising from bandwidth limitation must be overcome. Current cellular telephone systems operate on a frequency of 900 MHZ. Yet even with the use of sophisticated compression routines, the bandwidth is not wide enough to transmit the enormous amount of video and audio information that is required for quality motion pictures. Bandwidth limitation may not be a problem for high frequency satellite transmissions, but it is a problem for the comparatively low frequency radio transmissions.
Therefore, it is an objective of the present invention to overcome the above-mentioned bandwidth limitation problem and provide video communication capability to a radio frequency communication system.